Lubricant



Patented 25, 1941 PATENT OFFICE LUBBICAN '1 Melvin A. Dietrich, Claymont, Del., minor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application February 27, 1940, Serial No. 321,043

19 Claims. (Cl. 252-41) This invention relates to lubricants and particularly to lubricants having improved properties, the method of preparing such lubricants and the method of employing the same.

Under service conditions in internal combustion engines, lubricating oils tend to decompose and form deposits which adhere to the various metallic surfaces. Such deposits also serve as binders for materials of abrasive character, which enter the engine through the carburetor, crankcase vents and other openings to the outside air. Such v 'deposits if allowed to accumulate, result in sticking of piston rings, reduced clearances between bearings parts, clogged oil ducts, increased friction between moving parts, and a marked increase in the rate of wear of the moving parts. Also, under oxidizing conditions in storage and in service, lubricating oils tend to deteriorate and form insoluble oxidation products known as sludge. Under operating conditions in the engine, partial cracking of the lubricant may result in the formation of finely divided carbon. Both types of materials tend to separate from the lubricant and thus clog pumps, filters and heaters.

With the introduction of new alloy bearing materials, such as cadmium-silver and copper-lead alloy, possessing high load carrying capacity, it has been noted that some lubricating oils tend to develop corrosive products which cause etching of the bearing parts and result in failure of the bearing itself. Numerous materials, which have been proposed for addition to lubricating oils to improve the oils in other respects, have had either no beneficial effect on the tendency to develop corrosive products, or have tended to accelerate the formation of such corrosive products.

It is an object of my invention to provide lubricants with improved resistance toward the formation of adherent engine deposits. Another object of my invention is to provide oils with improved resistance toward deposition of insoluble sludge. A further object of my invention'is to provide oils in which any sludge formed will tend to remain in a dispersed state throughout the oils. A still further object is to provide lubricating oils having a reduced tendency to corrode hard bearing alloys of the type of cadmium-silver and copper-lead alloy' bearings. Other objects are to prepare new compositions of matter and to advance the art. Still other objects will appear hereinafter.

The above objects may be accomplished in accordance with myinvention by incorporating, in a viscous petroleum oil, a small proportion of an oil-soluble organic sulfonamide which is devoid of free sulfuric acid and of free sulfonic acid groups, that is, sulfonamides which contain no unneutralized sulfuric acid or sulfonic acid groups. I have found that, by thus treating such oils, the oils are improved in their resistance toward the formation of engine deposits, in their resistance against deposition of insoluble. sludge, any sludge formed is maintained in a dispersed state throughout'the oil, and, in the case of oils tending to corrode hard metal bearings, such corrosive tendency is materially reduced. Any organic sulfonamide, which is soluble in the oils and which contains no free sulfuric acid or free sulfonic acid groups, may be employed in accordance with my invention. The sulfonamide is characterized preferably by the presence in the molecule of 6 or more carbon atoms. They may be represented structurally by the formula wherein R. represents an acyclic, aiicyclic or aromatic radical which is preferably unsubstituted, but which may also contain substituents, such as amino, nitro, hydroxy, alkoxy, aryloxy, carboxy, halogen, cyano, or additional sulfonamide groups, and R and R" may be hydrogen or acyclic, aliphatic, heterocyclic or aromatic radicals, or they may represent a single organic radical doubly bonded to the nitrogen, or R and B" may form with the nitrogen a heterocyclic group containing the nitrogen in the ring. Preferably R and R" represent hydrocarbon radicals, and particularly aliphatic hydrocarbon radicals of atileast 4 carbon atoms. When the sulfonamides are to be employed primarily to inhibit corrosion of hard metal alloy bearings, or the formation of sludge, or both, the radical --NR'R" represents a diamine and particularly an alkylene diamine, in which the nitrogens are attached to separate S02 groups so as to form a disulfonamide of the diamine. It will thus be apparent that the preferred sulfonamides of my invention are those which, except for one or two groups, consist of carbon and hydrogen. I have N-dl-(2-ethylhexyl)p-toluenesulionamide Di-amyl-benzenesuiionamide sot-am N-(omega-cyanopentyl) p-toluenesulionamide S Or-NH-(C H:)r-C N N-(amyl-benzenesulionyl)morpholine l ll N,N'-di(p-amyl-benzen esulionyD-l ,2-proranediamine N,N'-di(p-toluenesulionyl)piperarine SOs-N N,N'-di(p-toluenesulionyl)-1,2-ethanediamine N-"Lorol" toluenesulionamidc' sol-NcLoml") White oil" sulfonamide (White oil)- SOPNHZ N-dibutyl "White oil sulfonamide (White i1")-SO2N(C4H9) a The term "Lorel" refers to alkyl groups corresponding, in carbon content and com sition to the acids occurring naturally in cocoanut oil, the suliona de being that derived from the mixture oi primary al mines which are, in turn, derived from such acids.

"The term "White oil" refers to the sulfonamide, prepared y treating a highly refined petroleum fraction, known as white oil and having the following characteristics Initial boiling point (ASTM)-283 0.

Dry point (ASlM)-324 C.

Saybolt Universal viscosity at 100 F. oi 37.2 seconds Specific gravity 20/l5.6 C.-0.7789

Refractive index at 20 C.-1.435l,

with chlorine and suliur dioxide in the manner described in Patent 2,174,506 to A. L For and treating the resulting sulionylchloride with ammonia and dibutylamine, respectively.

By the term a viscous petroleum oil as employed herein and in the claims, I mean an oil derived from petroleum and boiling within the lubricating oil boiling range and intend to include such oils when in the form of a grease, but to exclude the non-viscous oils, such as gasoline, kerosene, gas-oil and the like. By the term alkyl as employed herein and in the claims, I intend to include only saturated aliphatic hydrocarbon radicals. By the term aryl as employed herein and in the claims, I mean aromatic hydrocarbon radicals. By the term hydrocarbon, I mean the radicals consist of carbon and hydrogen alone. By the term alkylene, I mean a divalent aliphatic hydrocarbon radical.

The sulfonamides, employed in accordance.

with my invention, may be prepared by well known methods which are described in standard textbooks. reaction of the organic sulfonyl chloride with ammonia or with an amine. The compounds are, in genral, well known and are described in the literature.

The concentration of the sulfonamides in the oil may vary over a wide range. They may be employed in concentrations as small as 0.2% and as high as 20%. I generally prefer to employ the sulfonamides in the range of from about 0.2% to about 5.0% based on the oil. Usually,

, from about 0.25% to about 2% will be sufficient.

The sulfonamides of my invention may be incorporated in the oils by simple mixing and heating or they may be dispersed throughout the oil by more vigorous means such. as passage through a colloid mill, or solvents compatible with the oil may be employed. 1

The effectiveness of the sulfonamides, in reducing the quantity of deposits formed by an oil, was determined in the following manner.

A flat-top steel cylinder was prepared, 2 inches in height and 1 /2 inches in diameter, containing a peripheral spiral groove, A; inch wide and $4, inch deep, and cut at a pitch to form two threads per inch. This cylinder, dried and weighed, was heated by means of a copper bar to 250 C. and 30 cc. of the oil under test was dropped over a period of an hour onto the top surface and allowed to now down the spiral groove. After all the oil had been dropped on- They are most readily prepared by to the surface, the cylinder was maintained at are given in the following table: 10

Tut: 1

From these data. it is evident-that the use or a relatively small proportion a sulfonamide results in marked improvement in the general cleanliness of the engine parts and in reduction in ring wear with its attendant beneficial result on oil consumption. Inspection, of the data dealing with theoil condition at the end of the test. shows that the sulionamide has a generally beneficial effect on the oil characteristics, al-

Cylinder deposit St at 250 C.

Oil Compound fig Deposit ig? ir u u w u None-oontrol. I 31 Naphthenic base SAE 30 ML. N-dI-(Z-ethylhexvi) wtoluenesulionamide g :3 N-"Lorol" toluene-sulionamide 0: 6 27 13 None-control 79 Do Dl-amyl-benzenesulionarnlde".-. 0. 05 17 N-dlbutyl "White oil" sulionami 0. 5 33 58 D o None-control 131 rizwliite oil't'sirlionam1de... 1.0 101 23 one-eon 104 Pmmn SAE 20 ml Di-amyl-benzenesulfonamid 0. 5 67 35 None-control 125 Do N (omoga-cyanopentyl) p-toluene-sulronamide. 0. 5 08 20 N (amyl-benzenesulionyl)-morpholine 0. 5 115 8 In the above examples, as well as in a number of other cases, the deposits, formed by the oils containing the sulfonamides, were appreciably less adherent than those formedby the control oils. Even though the reduction in quantlty'oi! deposit is small. the reduced tendency of the I deposit to adhere to the metal surface in maintaining a clean engine.

The beneficial effects of the use of a sulfonamide in lubricating oils was further demonstrated by a 35 hour service test in a single cylinder Lauson engine. The results of this'test, using 0.5% of N-di(2-ethylhexyl)p-toluenesulfonamicle in a naphthenic base SAE 30 oil, are given in Table 2, wherein are given the data on thecondition of the oil and'engine at theend of the test.

will aid TAaLa 2 Single cylinder engine tests Conditions oi test: 35 hours operation at 1800 R. P. M. and full load; jacket temperature, 100 0.; oil temperature, 149 0.:

' Additive used .Engine condition (at end of test) N-dl (Z-ethylhexyl) None control p-toluenesulionamide (0.5%) V (rankcase sludge (upper). .Very light. Crankcase sludge (lower) Trace. (rankcase deposits. Clear. Heater sludge Very light. lpper piston carbon Non (onnecting rod color Piston top deposits grams. 0 73 0 60 Cylinder head deposits..do Ring loss. milligrams Oil consumption ..lbs./hr

' N-di-(2-etliylhexyl) Oil condition (at end of test) None-control p-toluen onamide (0.5%)

Sludge .mgJlO gms. 187 l6 5 Asphaltenes mg./ gms. 170 156 Viscosity rise. seconds at 210 F. (Saybolt Universal) l4; 1 12. 9 Carbon residue (00 son) percent by welght..-.----. l. 80 1. 64

vat which a 10 mg. loss though this effect is not as large as the improvement shown in general engine condition.

The beneficial eflect. of the compounds oi this invention on oil sludge. may be illustrated further by the following test, using N,N'-di(p-amylbenzenesulionyl) -1,2-propanediamine. In this test, grams of a naphthenic base SAE 30 011, containing 60 p. p. m. of iron (as iron oleate) and 0.5% of the sulfonamide, was placed in a 50 cc. beaker and heated for 30 hours at 175 C. in an oil bath, a control test being run simultaneously. Oil deterioration was determined by dilution of 10 grams oi the oxidized oil to 100 milliliters with special naphtha.'chilling for 3 hours at 0 C., and weighing the precipitated sludge. The results are:

Mg./l0 gm. Additive sludge None-control 345. 6 N .N'-di (p smyl benzenesulion l) 1 2 propane diamlne 75.8

while moist air rate of 2.7 liters per hour. Strips x 1%") oi cadmium-silver and copper-lead alloy bearing metals, as well as small soft steel pieces, are

suspended in the flasks, immersed half their' lengths in the oil.

They are removed at various intervals, washed with chloroform and acetone, and weighed. Froma curve, plotted from loss in weight against hours 01' exposure, the point, occurs per 10 grams of determined. Sludge is bearing metal, may be N-(alpha-naphthyl) p-amyl-benzenesulfonamide.

' sulfonamide.

Hour: to 10 mgJIOgms. loss sludgeaiia Compound Cadmium-silver Copper-lead Hours Mg./10 gms.

None-control Less than 20 Less than I) 72s N,N-(dl-p-toluone-sulionyl) plperazine 26 2| 401 None-control 21 U 70 ans N ,N'-di (p-toluene-suiionyl)-1,2-etbanediamine Above 70 Above 70 37 The above tests are given for illustrative purposes only. It will be readily apparent that many variations and modifications may be made therein, particularly in the compounds employed, their concentration, the conditions of use and other components of the lubricants without departing from my invention. For example, the sulfonamides of my invention may be employed in combination with other lubricant addition agents whereby the combined beneficial effects of the addition agents may be realized. Thus, my sulionamides may be employed in combination with phosphites, phosphates, chlorinated aromatic hydrocanbons, alkanolamines, other amines, long chain alcohols, extreme pressure agents, pour point depressants and viscosity improving agents. Examples oi suitable, combinations are tributyl phosphite with N-di-(2-ethylhexyl)p-toluenesulfonamide, tricresyl phosphate with N-mono-isobutyl p-toluenesulionamide, and diphenyl phosphite with N-dibutyl-white oil The sulfonamldes may be employed in compounded oils containing materials such as rapeseed oil, fish oils, sullurized sperm oil, olive oil and castor 011. They may be employed with advantage in greases and semi-solid lubricants in combination with various soaps and fillers. They can be employed in wax-bearing 11s and wax-free oils, in solvent-refined Oils and in oils refined by the customary acid treating methods.

Other sulionamides which may be employed in accordance with my invention are as follows:

N-ethyl p-amylbenzenesulionamide N-isobutyl di-amyl-benzenesultonamide N-ailyl p-toluenesuli'onamide N-methallyl p-toluenesulfonamide N-di-isobutyl p-propyl-benzenesulfonamide N-di-isopropyl p-isobutyl-benzenesullonamide N-dimethyl xylenesulionamide N-butyl xylenesulfonamide N-di-isobutyl naphthalenesulionamide N-methyl tetra-amyl-naphthalenesulionamide N-di-ethyl tetra-amyl-benzenesuli'onamide N-methyl N-butyl benzenesulfonamide N ethyl N phenyl tetra amyl benzenesulfonamide N di-octyl p-toluenesulfonamide N-dodecyl p-propyl-benzenesulionamide N-octadecyl p-allyl-benzenesulfonamide N-tetrahydrofurfuryl p-i'oluenesultonamide N-furfuryl p-toluenesulfonamide N-methoxybutyl p-toluenesulfonamide N-di-methoxyethyl p-toluenesulfonamide N-methoxypropyl p-amyl-benzenesulionamide N-phenoxy-ethoxyethyi p-toluenesultonamide N-(2-ethylhexyl) p-toiuenesulionamide N-di-ethyl di-chloro-benzenesulionamide N-di-amyl di-nitro-benzenesultonamide N-cyclohexyl cyclohexanesulionamide N-oleyl 4-methyl-cyclohexanesul1'onamlde ii -ethyl N-propyl 4-chloro-3-nitro-benzenesuli'onamide v N,N'-di- (p-toluenesulionyl) -1,6-diaminohexane N,N' di-(di-isopropyl-benzenesulionyl) -1,10-diaminodecane N,N'-di-(p-toluenesulionyl) -1,4-diaminobutane N,N' di-(p-(2-ethylhexyDbenzenesul1onyl) -1,2-

diaminopropane Bettafibeta' di (p-toluenesultonamido)diethyl e er N-(omega-carboxy-pentyl) p-toluenesulfonamide Hexadecanesultonamide N,N'-di-octadecyl 'lfi-naphthalenedisulionamide N,N'-di-(di-octadecyl) 1,5-naphthalenedisultonamide- N-octadecyl alpha-anthracenesullonamlde N-di-butyl p-toluenesulfonamide N-di-lsobutyl p-toluenesulionamide N-octyl xylenesulionamide .N-octyl 2,4,6-trimethyl-benzenesulionamide N- (di-amyl-benzenesulfonyl) thiomorpholine N-(di-amylbenaenesulionyl) carbazole Other suitable sullonamides may be prepared from mixed hydrocarbons derived from petroleum. such as naphthenes and parailin wax. An example of such a sulfonamide is N-naphthyl paraflin wax" sulionamide, which is prepared by reacting sulfur dioxide and chlorine with paramn wax to produce the parailin wax sulionyl chloride and then reacting such sulfonyl chloride with naphthyl amine.

While the lubricants of my invention are primarily intended for use in internal combustion engines, including Diesel engines, as well as those oi the spark-ignition yne. they may also be used advantageously in turbines, gears, wheel bearings and the like.

I claim:

1. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble organic suli'onamide. devoid of free sulfuric acid and free sulfonic acid groups.

2. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble organic sulfonamide 01 at least 6 carbon atoms, devoid of free sulfuric acid and free sulfonic acid groups.

3. A lubricantcomprising a major proportio of a viscous petroleum oil and a small proportion of an oil-soluble aryl sulfonamide, devoid of free sulfuric acid and free sulfonic acid groups.

4. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble N-substituted organic sulfonamide of at least 6 carbon atoms, devoid of free sulfuric acid and free sulfonic' acid groups.

5. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble organic sulfonamide, which, except for one to two groups, consists of carbon and hydrogen.

6. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble N-aliphatic substituted organic suli'onamide of at least 8 carbon atoms, devoid of free'sulfuric acid and free sulfonic acid groups.

7. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble N-aliphatic substituted organic sulfonamide of at least 6 carbon atoms, except for one to two groups, consists of carbon and hydrogen.

groups. consists of carbon and hydrogen.

ii. A lubricant comprising a major proportion which, 1

of a viscous petroleum oil and a small proportion of an oil-soluble di-(organic sulfonamide) of a diamine, devoid of free sulfuric acid and free sulfonic acid groups.

12. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble dl.-(organic sulfonamide) of a diamine. which, except for the two groups, consists of carbon and hydrogen.

13. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble di-(aromatic sulfonamide) of a diamine, devoid of free sulfuric acid and free sulfonic acid groups.

14. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of an oil-soluble di- (aryl sulfonamide) of an alkylenediamine.

15. The method of inhibiting the formation of sludge in a viscous petroleum oil, normally tending to form objectionable amounts of sludge in storage and in use, which comprises incorporating in the oil, in a small proportion sufficient to inhibit the formation of sludge, an oil-soluble organic sulfonamide, devoid of free sulfuric acid and free sulfonic acid groups.

16. The method of lubricating bearing surfaces which comprises maintaining between metallic bearing surfaces, one of which is an alloy selected from cadmium-silver and copper-lead alloys, a film of lubricating oil normally effective to provide lubrication of the bearing surfaces but which would normally tend to corrode the surface of the aforesaid'alloy, said lubricating oil having incorporated therein an oil-soluble organic sulfonamide devoid of free sulfuric acid and free sulfonic acid groups, in a small proportion sufllcient substantially to retard corrosion of the surfaces of said alloys by said oils.

1']. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of N-di(2-ethylhexyl) -p-tolenesulfonamide.

, 18. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of N-dibutyl-White o sulfonamide.

19. A lubricant comprising a major proportion of a viscous petroleum oil and a small proportion of N,N'-di(p-amyl-benzenesulfonyl) -1,2-

propanediamine.

MELVIN A. DIETRICH. 

